It is planned to delineate in normal volunteers and in obese patients the endocrine factors which may determine the relative degree of dietary induced thermogenesis from ingesting excess carbohydrate as opposed to fat, with particular attention to growth hormone, prolactin, glucagon and thyroid hormone. Methods to include study of circadian rhythms by continuous bloodsampling. It is planned to determine the effect initially in normal volunteers and also in diabetic and obese patients of evening as opposed to morning feeding on the circadian cycles of endocrine function, using methods of continuous sampling. It is planned to determine the effects of caloric restriction with and without ketosis and physical working capacity in obese subjects and to correlate capacity for high intensity and endurance exercise with the metabolic substrates used, the hormonal response to exercise, and the muscle glycogen.